METARs and TAFs answer two different questions
A METAR summarizes the conditions observed at an aerodrome at a specific time. A TAF describes the conditions forecast at the aerodrome during a defined validity period. Read them together: the METAR shows the current situation, while the TAF helps you understand how conditions are expected to evolve.
Decoding makes a report easier to read, but it does not replace the original report, an official weather briefing, meteorological charts or the pilot's assessment.
1. Always check the station, issue time and validity
The aerodrome identifier is normally followed by a date-time group. In 261220Z, 26 is the day of the month, 12:20 is the time and Z indicates UTC. A TAF also includes a validity period: 2612/2712 means from day 26 at 12 UTC until day 27 at 12 UTC.
Before interpreting anything else, confirm that the aerodrome and time window are the ones you need and that the report is sufficiently recent for its intended use.
2. Read every METAR in the same order
- Type and aerodrome: METAR or SPECI, followed by the ICAO code.
- Date and time: day, hour and minutes in UTC.
- Wind: true direction, speed, gusts and any directional variation.
- Visibility and weather: prevailing visibility, rain, showers, thunderstorms, mist or fog.
- Clouds: coverage, height in hundreds of feet and the presence of CB or TCU.
- Temperature and dew point: two values separated by a slash.
- Pressure: the QNH group, for example
Q1014. - Trend: any groups such as NOSIG or BECMG.
3. Identify wind, visibility and clouds
| Group | Interpretation |
|---|---|
23012KT | Wind from 230 degrees true at 12 knots. |
12012G25KT | Wind from 120 degrees at 12 knots, gusting 25 knots. |
9999 | Prevailing visibility of at least 10 kilometres. |
-SHRA | Light rain showers. |
SCT025 | Scattered clouds with a base 2,500 ft above the aerodrome. |
BKN012CB | Broken clouds with a base 1,200 ft above the aerodrome, with cumulonimbus. |
FEW, SCT, BKN and OVC indicate increasing cloud coverage. For operational ceiling assessment, BKN, OVC and vertical visibility are normally the relevant groups.
4. In a TAF, focus on the timeline
The first part of a TAF describes the initial prevailing conditions. Subsequent groups indicate when the scenario changes:
- FM introduces forecast conditions beginning at a specific time.
- BECMG indicates a gradual change within the specified period.
- TEMPO describes temporary fluctuations during the specified period.
- PROB30 or PROB40 expresses the probability of the associated conditions.
Do not read TEMPO or PROB as though they automatically applied to the entire forecast period. Always associate them with their accompanying dates and times.
5. Use decoding as a cross-check, not a shortcut
The interactive panel below highlights common groups and explains their purpose. Paste a report or load one of the training examples. If a group is not recognized, retain the original text and check it against the applicable documentation.
A practical briefing sequence
Start with the METARs for departure, destination and alternates. Compare them with the TAFs and previous reports, then broaden the briefing with radar, charts, wind, clouds, NOTAMs and aerodrome information. A single colour or decoded report cannot, on its own, represent the conditions along an entire route.